Conventional three-level power converters for railroad vehicles using two-element-inclusive power modules are configured such that, among four switching elements that are connected in series and from which upper and lower arms are configured, the combination of the outer-side switching elements (the switching element located on the highest potential side and the switching element located on the lowest potential side) and the combination of the inner-side switching elements (two switching elements located in the middle) are each configured from a two-element-inclusive power module and clamp diodes connected between the connection point of the two switching elements from which the upper arm is configured and the connection point of the two switching elements from which the lower arm is configured are configured separately by using a diode module (for example, Patent Literature 1 described below).